Correction to: The DBL Survey I: discovery of 34 double-lined double white dwarf binaries

Le résumé fourni par la source

In the original publication of this work, we presented the first instalment of the double-lined double white dwarf (DBL) survey, which seeks to find compact double white dwarf binary star systems where both stars are uniquely identifiable in their spectrum. We outlined the details of our survey with selection cuts and the observing strategy, presented many new double-lined systems and fit synthetic spectra to the sources to obtain atmospheric constraints. For almost all cases, this was performed with a hybrid approach of fitting our obtained spectra with Gaia DR3 parallaxes (Gaia Collaboration et al. 2023) and all-sky photometry. We also presented the WD-BASS pipeline that we created and employed to do so. The radiated flux of the two stars is given as an Eddington flux in synthetic grids. When handling spectra alone, the scaling of the two stars may be relative as the distance is irrelevant, with this scaling being |$R_1^2/R_2^2$| where subscripts 1 and 2 represent the two stars in the binary. Due to a coding mistake, the scaling coefficient was applied to the Eddington flux of the wrong star. No issues lie in the handling of photometry as this is part of a separate subroutine. In the majority of cases, the atmospheric solutions are hardly changed as both stars are similar in mass/size and hence |$R_1^2/R_2^2\approx 1$|⁠. In other cases where the square of the relative radius is larger, the inferred surface gravities change noticeably, as this variable compensates for the lacking flux contribution. The coding bug consequently leads to mistakenly quoted star masses. As we performed hybrid fitting with photometry and parallax measurements, the temperatures of the two stars is largely the same and the combined mass of the two stars is approximately equal since mass-temperature-radius relationships were employed. Our ability to identify single-lined double white dwarfs is unaffected. The determined surface gravities are also not wildly incorrect since the low-resolution spectra in the blue are dominated by the hotter star, and there is no unique detection of the second one to bias the fit. In any case, the mass ratios have changed at times where the size of the white dwarfs significantly differ, so we decided to refit all systems with this bug fix to WD-BASS. The outcome is supplied in Tables 1, 2, 3 and 4, and the corrected mass distribution of systems is plotted in Fig. 1. We draw particular attention to the fact that WDJ181058.67+311940.94 – the highest total mass system in the sample with a sub-luminous type Ia fate (Munday et al. 2025) – is negligibly impacted by the bug fix since here |$R_1^2/R_2^2$| is close to one. In that study, spectroscopic data from the Hubble Space Telescope Cosmic Origins Spectrograph is also fitted with an independent method that corroborates with our solutions. All conclusions to this system are unchanged. The mass distribution of compact DWD binaries where both star masses are quoted. The diagram is a reproduction of fig. 3 of Shen (2015). For this figure alone, M|$_1$| is the larger mass of the two stars for each system and M|$_2$| the smaller; all other mentions of star 1 or 2 in this study address indicate the hotter or cooler component, respectively. Systems plotted are DWDs in the literature where the mass of both components have an error better than 20 per cent of the mass of the star (see the data base upkept at github.com/JamesMunday98/CloseDWDbinaries for individual systems and references within). No filtering is applied on the orbital period for neither the literature sample nor the sample from our DBL survey, such that some objects will undergo the categorized events in over a Hubble time. The suggested evolutionary path for each category should be viewed as an approximate guideline only since stable mass transfer and AM CVn evolution are omitted. Acronyms first mentioned in the figure are as follows. sdB/sdO: hot subdwarf type B/O. R CrB: R Coronae Borealis. AIC: accretion-induced collapse. NS: neutron star. Fe CC: iron core-collapse. SN: supernova. The best-fitting parameters to the definite double-lined DWDs. Subscripts 1 and 2 represent the hotter and cooler star, respectively. Errors on the atmospheric constraints of the stars were obtained by combining in quadrature the statistical error from |$\chi ^2$| fitting with an external error of 1.4 per cent for T|$_{\text{eff}}$| and 0.042 dex for |$\log g$| (Liebert, Bergeron & Holberg 2005); however this should be considered a minimum due to extra degeneracy in two-star fitting. We emphasize caution again on interpretation of the masses for stars with a temperature below 5500 K. The ‘Exp’ column shows the total number of ID spectra exposures. The distance column includes the distance derived from fitting of the parallax with the inclusion of SDSS and PAN-STARRS photometry and a Gaussian prior using the Gaia parallax. The one exception where no photometric data were used was WDJ183442.33–170028.00 because of its very crowded field in the lining of the Milky Way and a distance (D) from the Gaia parallax is given and underlined. A reference is provided in the ‘Ref’ column when applicable if the system has already been discovered as a double-lined DWD or with an asterisk if the system was previously discovered to be a compact DWD but was not shown to have a double-lined signature. Note. References: (1) Kilic, Bédard & Bergeron (2021), (2) Kilic et al. (2020), (3) Kilic et al. (2021), (4) Sahu et al. (2023). The best-fitting parameters to the definite double-lined DWDs. Subscripts 1 and 2 represent the hotter and cooler star, respectively. Errors on the atmospheric constraints of the stars were obtained by combining in quadrature the statistical error from |$\chi ^2$| fitting with an external error of 1.4 per cent for T|$_{\text{eff}}$| and 0.042 dex for |$\log g$| (Liebert, Bergeron & Holberg 2005); however this should be considered a minimum due to extra degeneracy in two-star fitting. We emphasize caution again on interpretation of the masses for stars with a temperature below 5500 K. The ‘Exp’ column shows the total number of ID spectra exposures. The distance column includes the distance derived from fitting of the parallax with the inclusion of SDSS and PAN-STARRS photometry and a Gaussian prior using the Gaia parallax. The one exception where no photometric data were used was WDJ183442.33–170028.00 because of its very crowded field in the lining of the Milky Way and a distance (D) from the Gaia parallax is given and underlined. A reference is provided in the ‘Ref’ column when applicable if the system has already been discovered as a double-lined DWD or with an asterisk if the system was previously discovered to be a compact DWD but was not shown to have a double-lined signature. Note. References: (1) Kilic, Bédard & Bergeron (2021), (2) Kilic et al. (2020), (3) Kilic et al. (2021), (4) Sahu et al. (2023). The same as Table 1, but double-lined DWD candidates where the lower S/N ratio of the spectra of these targets is too difficult to conclude that they are double-lined definitively, although such a signature appears to be apparent. Continued observation and affirmation is encouraged. WDJ211927.07|$-$|030002.38 and WDJ225123.02+293944.49 had one exposure taken on one day followed by two on the other, and in both cases they appear double-lined in the first two exposures and slightly the third. The errors on the atmospheric constraints include an external error of 1.4 per cent for |${\rm T}_{\text{eff}}$| and 0.042 dex for |$\log g$| (Liebert et al. 2005); however this should be considered a minimum due to extra degeneracy in two-star fitting. The same as Table 1, but double-lined DWD candidates where the lower S/N ratio of the spectra of these targets is too difficult to conclude that they are double-lined definitively, although such a signature appears to be apparent. Continued observation and affirmation is encouraged. WDJ211927.07|$-$|030002.38 and WDJ2

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.